According to the working conditions of an oil field in the South China Sea, relying on 1 500 m underwater intelligent wellhead and Christmas tree project, a hydraulic actuated adjustable choke valve is developed. The design method of the valve core structure of the underwater choke valve is mainly introduced. In view of the general valve core structure design method, through theoretical analysis, considering different flow-by hole diameters, flow-by hole axial layout, total flow-by area, and so on, using finite element analysis tool, the flow characteristics of the choke valve core under different situations are analyzed, which ensures the chock valve is regulatory and prolongs the anti-erosion life of the valve core.